A man in his 30s who was also poisoned by tea purchased at the same shop has since recovered and is no longer hospitalized, said Rachael Kagan, a spokeswoman for the department of health.

The two victims purchased the tea from Sun Wing Wo Trading Co. separately in February and March.

The San Francisco Medical Examiner is working to determine the official cause and manner of death.

Xie and the surviving victim became critically ill — experiencing weakness and abnormal heart rhythms that required resuscitation — within an hour of drinking tea they had bought from the herbalist, officials said.

Investigators found the plant-based toxin aconite in tea samples the two provided to the health department.

Health inspectors removed products containing aconite from Sun Wing Wo Trading Co. while the merchant worked with the health department to track down the source of the toxic substance.

Each patient bought different blends of medicinal teas that may have had a common ingredient containing aconite, Kagan said.

Aconite has been used in Asian herbal medicine for thousands of years due to its anti-inflammatory properties. The plant’s raw flowers and roots contain a deadly cardiotoxin, which can be rendered safe when the plant is properly processed.

Aconite — also called wolf’s bane, monkshood, helmet flower, fuzi, caowu and chuanwu — is used to treat pains, bruises and other conditions.

Anyone who purchased the ingredient should stop consuming it and throw it out immediately, health officials said.

“Aconite poisoning attacks the heart and can be lethal,” Dr. Tomás Aragón, the city’s health officer, said earlier this month. There is no antidote for aconite poisoning.

Telephone calls to Sun Wing Wo Trading Co. were not answered on Monday.